Laser spectroscopy of the Lamb shift in muonic hydrogen

The muonic hydrogen atom in the 2s state provides the possibility of achieving high precision laser spectroscopy experiments from which a high precision value of the proton radius can be deduced. This will ultimately allow an increased precision in the test of QED in bound systems. Important progress has been made in recent years in the ability to stop muons in a low pressure gas target and in the understanding of the 2s-metastability in muonic hydrogen. As a consequence the 2s–2p laser spectroscopy experiment is now feasible and we present here the basic experimental concept considered by our collaboration. This revised version was published online in August 2006 with corrections to the Cover Date.     

Collisional effects on the collective laser cooling . of trapped bosonic gases

We analyse the effects of atom–atom collisions on a collective laser cooling scheme. We derive a quantum master equation which describes the laser cooling in presence of atom–atom collisions in the weak-condensation regime. Using such equation, we perform Monte Carlo simulations of the population dynamics in one and three dimensions. We observe that the ground-state laser-induced condensation is maintained in the presence of collisions. Laser cooling causes a transition from a Bose–Einstein distribution describing collisionally induced equilibrium, to a distribution with an effective zero temperature. We analyse also the effects of atom–atom collisions on the cooling into an excited state of the trap. Received: 18 June 1999 / Revised version: 24 September 1999 / Published online: 10 November 1999     

Absorption and percolation in the production of J/\psi in heavy ion collisions

We present a simple model with string absorption and percolation to describe the suppression in heavy ion collisions. The model qualitatively agrees with the NA50 data, and makes precise predictions for RHIC and LHC. Received: 10 March 2000 / Published online: 6 July 2000     

Films from soft‐core/hard‐shell hydrophobic latexes: Structure and thermomechanical properties

Structured latexes provide a promising route to hard coatings without the use of coalescing aids. We studied the thermomechanical properties of films from structured soft‐core/hard‐shell hydrophobic latexes. We found that the mechanical properties of these films were closely related to their very particular organization. When the rigid phase was continuous, whatever its volume fraction, the films exhibited a high elastic modulus. An analysis of the viscoelastic properties of the films provided a good method for obtaining information about the interphase between the hard shell and soft core of the latex particles. By varying the film structure through annealing or the particle composition (core/shell ratio, core crosslinking, etc.), we were able to tune the mechanical properties of the films. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2989–3000, 2000     

Rotating cylindrical systems and gravitomagnetism

We discuss gravitomagnetism in connection with rotating cylindrical systems. In particular, the gravitomagnetic clock effect is investigated for the exterior vacuum field of an infinite rotating cylinder. The dependence of the clock effect on the parameters of the stationary Lewis metric is determined. We illustrate our results by means of the van Stockum spacetime.     

The multichoice consistent value

We consider multichoice NTU games, i.e., cooperative NTU games in which players can participate in the game with several levels of activity. For these games, we define and characterize axiomatically the multichoice consistent value, which is a generalization of the consistent NTU value for NTU games and of the multichoice value for multichoice TU games. Moreover, we show that this value coincides with the consistent NTU value of a replicated NTU game and we provide a probabilistic interpretation. Received: May 1998/Final version: January 2000     

Ab initio conformational analysis of cyclooctane molecule

The potential energy surface (PES) for the cyclooctane molecule was comprehensively investigated at the Hartree–Fock (HF) level of theory employing the 3–21G, 6–31G, and 6–31G* basis sets. Six distinct true minimum energy structures (named B, BB, BC, CROWN, TBC, and TCC₁), characterized through harmonic frequency analysis, were located on the multidimensional PES. Two transition state structures were also located on the PES for the cyclooctane molecule. Electron correlation effects were accounted for using the Møller–Plesset second-order perturbation theory (MP2) approach. The predicted global minimum energy structure on the ab initio PES for the cyclooctane molecule is the BC conformer. A gas phase electron diffraction study at 300 K suggested a conformational mixture while an NMR study in solution at 161.5 K predicted the BC conformer as the predominant form. The equilibrium constants reported in the present study, which were evaluated from the ab initio calculated total Gibbs free energy change values, were in good agreement with both experimental investigations. The ab initio results showed that the low temperature condition significantly favored the BC conformer while above room temperature both BC and CROWN structures can coexist. © 1998 John Wiley & Sons, Inc. J Comput Chem 19: 524–534, 1998